Vitamin B12 status among pregnant women in the UK and its association with obesity and gestational diabetes

Background To evaluate vitamin B12 and folate status in pregnancy and their relationship with maternal obesity, gestational diabetes mellitus (GDM), and offspring birthweight. Methods A retrospective case-control study of 344 women (143 GDM, 201 no-GDM) attending a district general hospital and that had B12 and folate levels measured in the early 3rd trimester was performed. Maternal history including early pregnancy body mass index (BMI) and neonatal data (birthweight, sex, and gestational age) was recorded for all subjects. Results: 26% of the cohort had B12 levels <150 pmol/L (32% vs. 22% in the two groups respectively, p < 0.05) while 1.5% were folate deficient. After adjusting for confounders, 1st trimester BMI was negatively associated with 3rd trimester B12 levels. Women with B12 insufficiency had higher odds of obesity and GDM (aOR (95% CI) 2.40 (1.31, 4.40), p = 0.004, and 2.59 (1.35, 4.98), p = 0.004, respectively), although the latter was partly mediated by BMI. In women without GDM, the lowest quartile of B12 and highest quartile of folate had significantly higher adjusted risk of fetal macrosomia (RR 5.3 (1.26, 21.91), p = 0.02 and 4.99 (1.15, 21.62), p = 0.03 respectively). Conclusion This is the first study from the UK to show that maternal B12 levels are associated with BMI, risk of GDM, and additionally may have an independent effect on macrosomia. Due to the increasing burden of maternal obesity and GDM, longitudinal studies with B12 measurements in early pregnancy are needed to explore this link

Reduced GLP-1 Secretion at 30 Minutes After a 75g Oral Glucose Load is Observed in Gestational Diabetes Mellitus: A Prospective Cohort Study.

Glucagon-like peptide 1 (GLP-1) levels may be reduced in type 2 diabetes but it has not been established whether a similar impairment exists in gestational diabetes mellitus (GDM). We studied this in a prospective cohort study of pregnant women (n=144) during oral glucose tolerance test (OGTT). GLP-1, glucose and insulin were sampled at 30-minute intervals during a 2-hour 75g OGTT and indices of insulin secretion and sensitivity calculated. In a nested case-control study, women with GDM (n=19) had 12% lower total GLP-1 secretion (area under the curve; AUC) compared to age, ethnicity and gestational-age matched controls (n=19), selected from within the lowest quartile of glucose values in our cohort. GDM had lower GLP-1 response in the first 30 minutes (19% lower GLP-1 and 17% lower AUC) after adjustment for possible confounders. Their glucose levels began to diverge at 30 minutes of the OGTT with increasing insulin levels, and by 120 minutes, their insulin levels were three times higher. In a secondary cohort of 57 women, which included 'high-normal' glucose values, low GLP-1 AUC was independently associated with lower indices of insulin secretion and sensitivity. In conclusion, we have observed that women with GDM have lower GLP-1 response at 30 minutes of an OGTT and hyperglycaemia at 120 minutes despite significant hyperinsulinaemia